1. Field of the Invention
The present invention relates to a method for manufacturing a pulley integrated rotor for an electromagnetic clutch, in which a pulley member and a rotor member are integrated with each other.
2. Description of Related Art
Conventionally, as shown in FIG. 24, in an electromagnetic clutch manufacturing process, a pulley member 11 and a rotor member 12 are individually assembled and then welded together.
However, in the conventional manufacturing method, it is difficult to ensure a high concentric accuracy between the pulley member 11 and the rotor member 12 connected to each other, because of accumulation tolerances of the pulley member 11 and the rotor member 12, and connection tolerance between these members 11, 12. Therefore, the accumulation tolerances and the connection tolerance need to be strictly controlled, thereby increasing the manufacturing cost of the electromagnetic clutch.
Generally, a pulley groove 11a is formed by a plastic-forming process, such as a roll-forming process, to reduce the manufacturing cost. In the plastic-forming process, because a large force acts on the outer periphery of the pulley member to plastically deform the same, the pulley member has to be grasped firmly during the plastic-forming process.
However, it is difficult to grasp the pulley integrated type rotor at outer periphery thereof, because the pulley groove is formed at the outer periphery of the pulley member.